In general, rotating lids used for opening and closing pianos, laptop computers, and office equipment such as copy machines, and opening-and-closing lids of refrigerated compartments for reagents, analysis equipment, such as DNA sequencers, and antibody detection devices, are provided such that one end of the lid is supported by a rotary shaft, and the other end is rotatable in the vertical direction.
However, when the above described lid etc. is to be closed, the momentum of the closing lid tends to increase because the weight of the lid itself acts in the closing direction. When the momentum of the closing lid etc. is large, the lid or the main body may be damaged due to the impact when lid closes. In particular, a heavy lid tends to slam shut, causing damage to the lid and so on.
Therefore, to prevent such damage, various techniques for reducing the momentum of closing the lids etc. have been proposed (for example, see Patent Document 1).
Patent Document 1
Patent Document 1: Japanese Unexamined Patent Application, Publication No. HEI-6-81876 (page 2, FIG. 7, etc.)